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New Zealand scientists say they have found a way to use a strain of the common insect fungus Metarhizium to treat beehives infected with varroa mites.
The discovery opens up potential to develop an organic solution to varroa.
Metarhizium is a fungus harmless to humans which occurs widely and is known to infect a large number of insects.
It has previously been used as a biocontrol for plant pests, but attempts to develop a commercial product for use in hives have failed because the fungus is rapidly removed by bees during their normal cleaning of the hive.
"This strain of Metarhizium is varroa's worst enemy," said a honeybee expert at the state-owned science company Hortresearch, Mark Goodwin, "We had an excellent biocontrol for varroa but were being thwarted by a bunch of very house-proud bees".
But Dr Goodwin said his team had found a way to keep enough fungus within the hive to control the mites by using it as a living organism rather than a pesticide treatment. "We found a way to make Metarhizium part of the overall hive ecosystem," he said.
"The bees accept it, and the fungus is able to get on with killing varroa."
Hortresearch acting chief executive Bruce Campbell said the research could be commercialised very quickly and his scientists are already working with an international partner to put a treatment on sale before the end of the year.
Work announced earlier this year, bees genetically-resistant to varroa, was also progressing well.
Dr Campbell said beekeepers did not like using the existing chemical treatments, as there was potential for varroa to become resistant.